1. Field of the Invention
The present invention is related to valves and valve devices for automatically closing a valve to stop the flow of a fluid in a condition when the device is subjected to shock and vibration forces such as experienced during an earthquake. The invention is particularly related to triggering mechanisms of the valves which are actuated by earthquake movement to initiate closing of the valves.
2. Description of the Prior Art
Valves which respond to shock and vibration forces initiated by an earthquake are known, comprising various types of triggering structures which are actuated automatically to close a fluid path built inside of the valves.
U.S. Pat. No. 4,915,122 issued on Apr. 10, 1990 discloses a shock actuated valve which uses a ball motion to actuate a valve due to earthquake forces and similar shock forces. The device modifies the pedestal on which the ball rests to allow gravity forces to act on the ball once it has been moved from its position of rest to aid actuation of the shock actuation control mechanism. The modification of adding a step to the pedestal upper perimeter surface improves the accuracy for the elapsed time for the valve to be actuated once a specified force has been sensed. In prior art mechanisms the motion may be compounded by the ball not initially actuating the shock actuation control mechanism due to the ball moving, but rebounding or retreating from an initially urged position to be moved to a second position by the forces. Theses non-actuating motions of the ball delays valve closure which may increase the possibility of damage during an earthquake.
U.S. Pat. No. 6,926,025 issued on Aug. 9, 2005 discloses a vertical shock responsive fluid valve assembly which is capable of automatically closing a fluid valve in response to earthquake forces or other shock forces of a predetermined magnitude. The vertical shock responsive valve assembly has a flow control mechanism having a cradle that holds a movable ball in a recess at a point perpendicular in relation to a horizontal base plate, where the ball can be rotated 360 degrees in any direction during seismic actions or other shock forces and rolls out of its recess at a predetermined force such that it ricochets off a housing cover covering the cradle and pushes a trip fork mechanism having an elongated wall to provide additional leverage when the force strikes the trip force mechanism that is mounted on a pivoting mechanism, thereby releasing a swing arm which has a disc on the end that functions as a plug for an opening in the valve body to interrupt gas or fluid flow therein.
Therefore, there is a significant need to provide either a vertical or horizontal valve assembly actuated by the earthquake or other shock forces at a predetermined magnitude which can automatically close the respective vertical or horizontal flow of a fluid to significantly improve versatility of the devices.